mineral

Quartz nodule (River pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to translucent with iron-oxide (rusty) staining; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white to translucent with iron-oxide (rusty) staining
Luster: Vitreous to waxy

Identified April 1, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through hydrothermal processes or within igneous rocks like granite. This specific specimen has been redondeed (water-worn) over geological time in a high-energy aquatic environment like a riverbed or shoreline.

Uses & applications

Common quartz is used in concrete, glass manufacturing, abrasives, and as a landscaping stone. Smooth pebbles like this are often used in home decor or as worry stones.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. This specimen shows 'chatter marks' or internal fractures typical of stones that have collided with others in a river current.

Field identification & locations

Identify in the field by its ability to scratch glass and its lack of cleavage. It is found globally in almost all geological environments, particularly in sediments and beach deposits.